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<br />Biological Data <br /> <br />The BLM has conducted field surveys of the fishery resources on this stream and have found a <br />natural environment that can be preserved. As reported for this reach of stream in the BLM letter <br />to the CWCB " Fishery surveys indicate that the stream environment is in stable condition, and <br />supports a self-sustaining brook trout fishery. Spawning substrate, pool availability, and food <br />availability are good for salmonids. However, vegetative cover is limited in this reach, <br />underscoring the importance of protecting flows to maintain adequate temperatures during the <br />late summer and fall" (see CDOW Fish Survey in Appendix B). <br /> <br />Field Survey Data <br /> <br />BLM staff used the R2Cross methodology to quantify the amount of water required to preserve <br />the natural environment to a reasonable degree. The R2Cross method requires that stream <br />discharge and channel profile data be collected in a riffle stream habitat type. Riffles are most <br />easily visualized, as the stream habitat types that would dry up first should streamflow cease. <br />This type of hydraulic data collection consists of setting up a transect, surveying the stream <br />channel geometry, and measuring the stream discharge. Appendix B contains copies of field <br />data collected for this proposed segment. <br /> <br />Biological Flow Recommendation <br /> <br />The CWCB staff relied upon the biological expertise of the cooperating agencies to interpret <br />output from the R2Cross data collected to develop the initial, biologic instream flow <br />recommendation. This initial recommendation is designed to address the unique biologic <br />requirements of each stream without regard to water availability. Three instream flow hydraulic <br />parameters, average depth, percent wetted perimeter, and average velocity are used to develop <br />biologic instream flow recommendations. The CDOW has determined that maintaining these <br />three hydraulic parameters at adequate levels across riffle habitat types, aquatic habitat in pools <br />and runs will also be maintained for most life stages of fish and aquatic invertebrates (Nehring <br />1979; Espegren 1996). <br /> <br />For this segment of stream, two data sets were collected with the results shown in Table I below. <br />Table I shows who collected the data (Party), the date the data was collected (Date), the <br />measured discharge at the time of the survey (Q), the accuracy range of the predicted flows <br />based on Manning Equation (240% and 40% of Q), the summer flow recommendation based on <br />meeting 3 of 3 hydraulic criteria and the winter flow recommendation based upon 2 of 3 <br />hydraulic criteria. <br /> <br />Table I: Data <br />Party <br />BLM <br /> <br />Date <br />09/17/1998 <br /> <br />Q <br />1.91 <br /> <br />250%-40% <br />4.8 - 0.8 <br /> <br />Summer (3/3) <br />1.8 <br /> <br />Winter (2/3) <br />0.25(1) <br /> <br />BLM Bureau of Land Management DOW - Division of Wildlife <br />(1) Predicted flow outside of the accuracy range of Manning's Equation. ? = Criteria never met in R2CROSS Staging Table. <br /> <br />Biologic Flow Recommendation <br />The summer flow recommendation, which meets 3 of 3 criteria and is within the accuracy range <br />of the R2CROSS model is 1.8 cfs (See Table I). The winter flow recommendation, which meets <br />2 of 3 criteria but is outside the accuracy range of the R2CROSS model is 0.25 cfs (See Table I). <br />It is our belief that recommendations that fall outside of the accuracy range of the model, over <br />250% of the measured discharge or under 40% of the measured discharge may not give an <br />accurate estimate of the necessary instream flow required. In these cases, CWCB staff relies <br /> <br />- 3 - <br />